Featured Articles

Paradox of Progress: Reality vs. Perception of Pork Safety in Modern Swine Production

28 June 2013

Reviewing the evidence relating biological hazards in pork to changes in the US swine industry structure, Peter Davies of the College of Veterinary Medicine at the University of Minnesota in the US has concluded that pork is safer than in any previous era. He was speaking at the 2103 London Swine Conference.

The Paradox of Progress

Much of human endeavour and creativity is devoted to the goal of progress – that through advances in diverse arenas of science, technology, modernisation, liberty, and democracy we can deliver a better quality of life for mankind. ‘The only constant is change’ is a fairly tired cliché, but history suggests that change is not constant but is exponential.

Futurist author, Ray Kurzweil, states that: 'Analysis of the history of technology shows change is exponential, contrary to the common ‘intuitive linear’ view. So we won’t experience 100 years of progress in the 21st century – it will be more like 20,000 years of progress.'1

The concept of the ‘paradox of progress’ has been traced to Adam Smith in the 18th century2, and has been the title of several books that have variously observed paradoxes such as:

The more we know, the more we have to discover

Higher economy and consumerism leads to more stress as people work more and society falls behind

As society moves forward, more problems are created

The better things become, the worse they are perceived.

The North American swine industry has been a case study of accelerating change, and the author has heard ‘senior’ swine veterinarians speak of ‘100 years of change in 10 years’ when discussing their experiences in the industry. We can look at many facets of the industry and see evidence of substantial ‘progress’ in intensive swine production. Yet the US industry is perceived to be ‘worse’ than its preceding incarnations, and is accused almost daily of being responsible for, or contributing to, a range of societal problems.

Platforms of opposition to intensive livestock production are multifaceted: sociological (e.g. loss of small farms and impact on rural communities; anti-corporate sentiment); ethical (e.g. questioning the acceptability of animal housing conditions, traditional farming practices such as castration, and carnivorism itself); environmental (e.g. odour, pollution, carbon footprint) and sanitary (e.g. zoonotic and emerging disease; antimicrobial use and resistance; occupational health and food safety). Different issues resonate more or less with different people, and the deliberate amalgamation and blurring of disparate issues has been an effective tactic for galvanizing opposition to modern livestock production.3

All industries need criticism which serves to steer industry practices in the directions desired by the wider community. Career critics of the food system in general, and intensive animal production in particular, are primed to pounce on any event that can be portrayed as industry malfeasance. But to be constructive in a social context, criticism must be founded on accurate and comprehensive analysis that captures the inevitable trade-offs inherent in changes to, or constraints upon, industry operations.

The author uses the example of pork safety to discuss what changes in the US industry have meant for pork safety. Pork safety is perhaps the most convincing illustration of the gap between a history showing measurable progress that is accompanied by paradoxically negative perceptions.

How Do We Get Our Food?

Food is an intimate element of the human experience and there are all manner of passionate opinions about what we should eat, and how it should be produced, procured and prepared. Engaging authors such as Michael Pollan and Eric Schlosser, and films like Food Inc., have inspired a mass of neoromantic ‘locavores’ who disparage almost every facet of the mainstream commercial food industry, with intensive animal production a preferred target.

The ability for average citizens, wisely or not, to indulge their dietary or non-dietary preferences is one hallmark of progressive societies. In developed countries, the transformation of food procurement from hunter-gathering and subsistence agriculture (i.e. the pinnacle of eating local) to one-stop supermarkets straddling complex global supply chains is virtually complete and the vast majority of citizens play no part in producing their food. As with electricity or running water, the facility with which those living at high latitudes can select from a panoply of fresh fruit and vegetables, among other foods, year round is largely taken for granted – yet would be sorely missed were their availability suddenly interrupted. It is hard to envision that, from the perspective of the average consumer, the evolution of the food industry over the last 100 years can be represented as anything other than progress, at least in terms of efficiency and convenience of accessing diversity of affordable dietary options, and in freeing time for pursuit of other activities for work and leisure.

The strong positive correlation between wealth and meat consumption, seen among and within countries, reflects the fact that animal proteins are preferred protein sources across the majority of cultures. The bulk of the socioeconomic spectrum of North Americans and Europeans has lived high on the metaphorical hog for several generations, with the affordability of the finer meat cuts leaving the once common consumption of offal and other lower value animal products largely to those of limited means or being channelled into export markets.

On-going growth in developing economies such as China and India underpins bullish projections of future global demand for pork and other meats. However, contemporary discussions of projected world population growth, its implications for land use, and the environmental impact of food production raise complex questions about the future of meat consumption.

Global population growth and wealth is revealing inevitable tensions between the desire to consume goods and services and our ability to sustainably provide them in a finite and increasingly crowded planet. These complex problems are beyond the scope of this discussion but can be distilled down to a simple question: if the world of the future is going to have a swine industry, what should it look like?

Industrialisation of Swine Production and Pork Safety

Media reporting and blogging about the safety of the food (and particularly meat) supply seems to be singularly fertile ground for misinformation. The parade of ‘worrying’ factoids and reports is endless, with a recent Consumer Reports study perhaps raising an already elevated bar of scaremongering founded on pseudoscience.4 In 2012, the author reviewed evidence related to biological hazards in pork in relation to changes in the US swine industry structure, and concluded that the evidence indicates pork is safer than in any previous era.5

The following discussion presents some of the salient observations made in that publication (detailed references are provided in the original publication).

Foodborne parasites

The foodborne parasites Taenia solium, Trichinella spiralis and Toxoplasma gondii have arguably been responsible for the majority of suffering from pork-borne illness throughout the history of mankind, and remain important problems in many developing countries. The Food and Agricultural Organization cites estimates that some 50 million people worldwide harbour the adult T. solium tapeworm, and up to 50,000 deaths per year are attributable to cysticercosis. T. solium is also largely responsible for the four-fold higher rates of epilepsy in developing versus developed countries. This parasite thrives where sanitation is poor and traditional, free-range/ scavenging pig production is practised. However, T. solium is off the radar screen of the US food safety dialogue and it has been suggested that elimination of T. solium from Europe and North America was largely a consequence of economic development that made small-scale, subsistence pig rearing uneconomic. Methods of modern confinement swine production virtually eliminate any risks of pork-borne transmission of T. solium.

During the 1940s, about 400 clinical human trichinosis cases (and 10 to 15 deaths) were recorded annually in the USA. The incidence declined to about 60 cases per year by the 1980s, primarily through better control of trichina infections on pig farms. From 1997 to 2001, only 72 human trichinosis cases (and none fatal) were recorded by the CDC and consumption of wild animals had far surpassed pork as the most common source of infections. Once a major pork-borne pathogen, modern production systems have relegated T. spiralis to little more than an historical footnote for commercial pork industry.

Toxoplasma gondii is one of three pathogens responsible for three-quarters of the fatalities attributed to foodborne infections in the US. Some 400 to 4,000 US children are born with congenital T. gondii infection each year, and the societal cost of congenital toxoplasmosis alone was estimated to be up to $8.8 billion annually in 1990. Just 25 years ago, T. gondii occurred in 40 per cent of US sows and 20 per cent of market hogs, and undercooked pork was considered an important source of human infection. Its prevalence has since been reduced by over 90 per cent in today’s commercial industry.5

The reduction of these agents to a state of relative inconsequence in modern pork production in developed countries is a notable public health accomplishment that has gone largely unheralded.

Foodborne pathogens

Relative to the parasitic hazards discussed above, the major bacterial foodborne pathogens of concern to the swine industry (Salmonella, Campylobacter, Listeria, Yersinia) have much more complex epidemiology, and progress with on-farm control has been minimal. These organisms have their primary ecological niche in the intestinal tracts of healthy birds and mammals. Their presence on meat stems from contamination events that can occur anytime during harvest and processing until meat is served. Contamination risk during harvest and processing is a function of both on-farm exposure and slaughter hygiene, and both pre-harvest and post-harvest arenas are rational targets for interventions. Salmonella remains the pre-eminent bacterial hazard in most pork industries and - apart from the northern Nordic countries where uncommonly low Salmonella prevalence supports the possibility of excluding Salmonella from pig populations - most countries identify reduction rather than elimination of Salmonella to be a more attainable goal in pork production.

Knowledge and experience with pre-harvest control of Salmonella dwarfs those of other enteric bacterial pathogens yet there remains a dearth of validated, evidence-based interventions for pre-harvest Salmonella control. Despite the appealing logic for pre-harvest control of foodborne pathogens, the task has proven daunting and opinions remain divided on the feasibility and costeffectiveness of pre-harvest control programs for Salmonella in pigs. Investment in pre-harvest surveillance and control has been widespread in western Europe, but much less in North America where substantial reduction of Salmonella contamination of hog carcasses has been achieved by improvements in the post-harvest sector.6 The data generated by the Danish National Salmonella control programme has provided much insight into the challenge of pre-harvest control, and indicate that benefits from pre-harvest control would most likely accrue in low prevalence regions and small processing plants. It was concluded that in medium to high prevalence scenarios, even drastic reductions at herd level may yield only limited benefits in reducing the prevalence of positive carcasses.7 While advances in process control and new interventions during slaughter and processing have yielded measurable improvements in meat hygiene, considerable investments in pre-harvest control of Salmonella appear to have yielded only modest benefits. Despite much noise claiming the contrary, there is negligible evidence that Salmonella are more prevalent in intensive swine operations than in feral pigs, historic swine operations in the pre-confinement era, or swine raised in less intensive systems in developing countries.5

The most vocal proponents of pre-harvest control of foodborne enteric bacteria have combined a degree of epidemiological naïveté with a belief (regardless of the vacuum of supporting data) that ‘the problem’ was attributable to modern farming methods and, specifically, confinement production. In my opinion, the least equivocal outcome from fifteen of so years of pre-harvest research is that elimination of organisms that are normal flora (Campylobacter coli), or common commensals (Salmonella, Listeria, Yersinia) of the swine intestinal tract will not be achieved by facile interventions in farm management.

The complexity of the epidemiology of Salmonella and other enteric organisms is difficult to overstate, but is dominated by the fact that these organisms are commonly carried by, and shed in the feces of, healthy animals. Development of valid and reliable pre-harvest interventions to control bacterial foodborne pathogens remains the pre-eminent challenge for researchers in pork safety.

In contrast, post-harvest interventions, and most notably food irradiation, present proven, safe and relatively low-cost options for risk reduction for multiple hazards which should be pursued for higher risk items such as ready-to-eat and comminuted meat products. However, implementation of food irradiation in the meat industry remains enmeshed in ideological opposition. Those who oppose irradiation of higher risk meat products on the grounds that producers must take more responsibility for food safety would appear to be more motivated to constrain the production sector than to protect consumers from foodborne illness. Regardless, measurable improvements in meat hygiene have been achieved by improved slaughter processes. A recent attribution study estimated pork to be responsible for less than one per cent of human salmonellosis attributed to contamination of raw meat, poultry and egg products in the USA,8 and available data indicate that commercial pork produced in the USA is currently safer than at any time in history.5

Future Developments

Looking forward, the international marketplace for pork will require incrementally more demanding standards for pork safety. In order to remain competitive in premium markets, exporters must achieve and assure very low risks for chemical, physical and microbial hazards, and any failures have the potential to incite crippling consequences for market access.

Quality assurance programmess implemented on farms should be adequate to manage the majority of physical and chemical hazards, as well as parasitic foodborne hazards.

Unless major research breakthroughs occur in pre-harvest control of enteric bacteria, improved meat hygiene and slaughter processing will continue to be the mainstay for microbiological safety.

An important challenge for the industry is to inform the general public of the real advances that have been made in pork safety and balance the misinformation of those who remained convinced that things have gotten worse regardless of the facts.

8. Guo, C., et al. (2011). Application of Bayesian techniques to model the burden of human salmonellosis attributable to U.S. food commodities at the point of processing: adaptation of a Danish model. Foodborne Pathog. Dis. 8, 509-516.

Further Reading

You can view other papers from the 2013 London Swine Conference by clicking here.